Well, even w/ the pick-up taped to the magnet, no combination of any 2 pins on the mount would give me a continuous loop w/ the meter, so I took a leap of faith and lopped off the iBike wheel pick-up and spliced on an old Sigma Sport pick-up, and sure enough, the iBike is reading the wheel speed again. So, it would appear that the pick-up went bad. (A close inspection of the pick-up showed a crack on the concave bottom side of the molded pick-up unit - I suspect from several years of it being zip-tied to my essentially flat inner fork leg (its a wide, blade-style fork, so the inner surface is flat, while the pick-up is concave, so likely underwent distortion over time being zip-tied to a flat surface).
I'm wondering if this might help w/ some of the rain-related problems I've had at times, too - sometimes in the rain, or even just on really wet roads after a rain, the iBike will stop measuring wheel speed - maybe water was working its way into the pick-up through the crack.
Given the seeming prevalence of wider fork legs these days, it might be worth iBike looking at modifying the pick-up design at some point to get rid of the concave back, or maybe provide a little extra hunk of plastic that would fit into and fill the concave for use w/the flatter fork legs, if others have experienced similar problems. (Or, maybe they need to put out an update to the manual instructing those of us who are zip-tie-happy to go easy on the zip-tie tension when attaching the sensor to a flat fork leg...
